Miscella refining



Patented Aug. 7, 1951 MISCELLA REFINING Robert G. Folzenlogen,

Hamilton County, Ohio, assignor, by mesne assignments, to The BuckeyeCotton Oil Company, Memphis, Tenn, a corporation of Ohio No Drawing.Application June 27, 1949, Serial No. 101,683

12 Claims. i

This invention relates to the refining of solvent extracted vegetableoils, and more particularly to the refining of such oils in the presenceof the extraction solvent.

One of the disadvantages which has deterred wider adoption of refiningprocesses involving the addition of an aqueous alkaline refining agentto the solvent solution of extracted oil for the purpose of neutralizingthe oil and of reducing color is the rather low emciency of colorremoval. Usually the recovered oil from such refining is subjected to asecond refining in order that its color may be suificiently light tomeet current standards for edible use, as in shortening for example.

It is therefore an object of the present invention to provide animproved process of refining solvent extracted vegetable oils in thepresence of the extraction solvent, whereby color removal from the oilis markedly improved.

A further object is to provide a process for the alkali refining ofsolvent extracted vegetable oils in the presence of the extractionsolvent, in which process color removal from the oil is efiicientlyeffected in a shorter time and with the use of less alkali.

Other objects and advantages will appear in the following description ofthe various embodiments of the invention.

It has been observed in the course of my association with the refiningof oil-solvent solutions (sometimes referred to in the art as miscellas)that color removal may be improved by continued agitation of themiscella with the refining lye over a long period or by the use of anincreased quantity of the refining lye. However, either of theseexpedients is conducive to excessive oil saponification and an attendantincrease in oil loss.

I have found that agitation of the refining lye and miscella in thepresence of certain non-ionic ethers markedly improves color removal andpermits reduction both in the agitating time and in the amount ofrefining lye hitherto necessary for desired color reduction. The reasonfor the effectiveness of the non-ionic ether is not understood but I amof the opinion that the action is not due solely to emulsificationefiecting more intimate-contact. In support of this position I point tmy observations that some of the ethers employed are not recognized asemulsifying agents and that other materials which are well known in theart as emulsifying agents, such as soaps, monoglycerides, alkylsulfates, alkyl benzene sul- Columbia Township,

2 fonates and other sulfates and sulfonates having emulsifying action,have substantially no power to improve color removal during refining.

In accordance with my invention, the lye is intimately mixed with themiscella in the presence of at least one non-ionic ether compound,liquid at about F., and of the group consisting of (1) ethers ofpolyhydric alcohols, said alcohols containing from two to three hydroxylgroups and having from two to eight carbon atoms in the carbon skeleton,and (2) non-ionic derivatives of such of said ethers as containunreacted hydroxyl groups.

It is to be understood that although ethers used in the practice of myinvention are identified as ethers of polyhyclric alcohols, such ethersmay be iormed from compounds other than polyhydric alcohols, such aspolyhydric alcohol anhydrides for example.

Various types of non-ionic ether compounds may be employed in thepractice of the invention as will be apparent from the list of compoundsgiven below. It will be noted, moreover, that with respect toderivatives of those ether compounds which contain unreacted hydroxylgroups, such derivatives may be formed, for example, by reaction of thehydroxyl group with carboxylic acids, compounds containing an unreactedalcoholic'hydroxyl group, phenols, amines and mercaptans. Thus, forexample, tetraethylene glycol or the monoethyl ether of ethylene glycolper se may be used, or those non-ionic derivatives which are liquid atabout 80 F. and which may be formed by reaction of other compounds withthe unreacted hydroxyl groups of the glycol may be employed. Withrespect to such derivatives, it is important to observe that the successof the in vention does not depend on the type of derivative employedprovided that it is liquid at about 80 R, that it is non-ionic, and thatit contains the ether groups intact. Having such chemical and physicalproperties the derivative (or the original ether) can be used in thepractice of my invention and an improvement in the ease of color removalduring miscella refining will be observed.

As will be noted from the following detailed description, the essentialdistinguishing features of the refining procedure of my invention overthose hitherto employed are in the use of the ether compound and in theattendant permissible reduction in lye usage and agitating time.

amass? The miscella coming from the extraction step usually containsmore solvent than oil, but my refining procedure does not require largequantities of solvent and it may be desirable from the standpoint ofeconomy in handling, storage, etc, to remove a portion of the solventbefore performing the refining operation. Such reductions in the amountof solvent may be achieved by the usual evaporation facilities known inthe art. I prefer to carry out the refining procedure on miscellascontaining from about 25 per cent to about 50 per cent oil.

I have found also that it is preferable to refine the miscella withreasonable promptness after recovery from the extraction procedure.Under the same conditions of operation it will be found that colorreduction in the case of fresh miscella will be somewhat greater thanthat obtained in the refining of aged miscella. Thus an advantage willbe gained by arranging to refine the miscelia promptly as it isdelivered from the extraction unit or from the miscella concentration.

In such practices involving refining substantially immediately afterextraction or miscella concentration, the temperature of the miscellamay be well above 100 F. as it is charged to the refining equipment.Cooling the miscella before addition of the refining lye is unnecessary.The temperature at which the refining agent is mixed with the miscellain the presence of the nonionic ether compounds is therefore not alimitation. Ordinarily the temperature will range from about 80 F. tojust below the boiling point of the miscella. According to myexperience, however, good color reduction in minimum time is effected attemperatures between 130 to 140 F,, preferably at about 135 F. when the.miscella is constituted of about 40 to 50 per cent oil in commercialhexane. Such temperatures of course will also vary depending on thesolvent used in the extraction, lower boiling solvents of courserequiring lower temperatures if the refining is conducted at atmosphericpressure.

The advantages of my invention are realized when the miscella isconstituted of extraction solvents other than hexane. Thus improvedresults in color reduction are also noted in the case of miscellasformed by the use of extraction solvents such as benzene, heptane.commercial mixtures containing such hydrocarbons, and other aliphaticand aromatic hydrocarbon extraction solvents and solvent mixtures knownin the art. The invention is of particular advantage, of course, in therefining of those miscellas formed in the use of solvents which dissolvea considerable quantity of highly colored constituents from theoil-bearing meats.

The concentration of the refining lye will vary, depending on theproportion and kind of minor constituents contained in the oil anddissolved in the miscella. Higher concentrations are preferably usedwhen the concentration of free fatty acid and color constituents ishigh. However, the necessary adjustments to compensate for suchvariations in miscella constitution are known to those versed in the artand have no influence on the advantages of using the nonionic ethers inaccordance with my invention. By way of illustration, however, I havefound that aqueous solutions containing from about 5 per cent to about20 per cent sodium hydroxide may be used, final choice depending on therefiners judgment.

As indicated generally above, practice of the instant invention makespossible a considerable saving in lye usage. For example, before mydiscovery of the advantageous action of non-ionic ethers in reducingcolor, it was necessary to use 200 to 225 per cent of the maximum percent sodium hydroxide prescribed by the rules of the National CottonseedProducts Association in the regular refinin of hydraulic cottonseed oilsof the same free fatty acid content as oleic acid (per cent NaOH=percent F. F. A./5.2+.54). Even with such large caustic usages, agitationtimes of 70 to minutes were required to obtain desired color removal.Use of the present invention not only permits an appreciable reductionin the time of agitation required to effect color removal, but alsopermits reduction in the caustic usage to 100-175 per cent of themaximum prescription above referred to for hydraulic oils of comparablefree fatty acid content. Under normal conditions and with normal hexanemiscellas, obtained in the extraction of cottonseed oil for example,125-150 per cent of maximum will suffice. Both of these permissiblereductions are conducive to lower refining loss. as thou versed in theart well know.

The following examples will illustrate 'the manner in which my inventionmay be practiced, but it is to be understood that the procedures thereindescribed are merely illustrative and are not intended to be limiting.

Example 1.-By titration with N/10 sodium hydroxide solution, theapparent free fatty acid (as oleic acid) content of a concentratedcottonseed oil miscella containing about 40% oil and about 60% hexanewas determined as 2.6%. From this determination 125% of maximum per centsodium hydroxide prescribed by the rules of the National CottonseedProducts Association for hydraulic pressed cottonseed oil of comparablefree fatty acid content was calculated as 33%, or 10.8% of 12% sodiumhydroxide solu- 189.5 .parts by weight of the miscella were chosen forthe refining procedure of my invention. This quantity of miscellarequired 20.5 part by weight of 12% sodium hydroxide solution on thebasis of the foregoing calculation.

To the miscella at 130 1". were added .13 part by weight ofpolypropylene glycol of about 400 molecular weight. This amount ofglycol was about 0.625% of the weight of the lye calculated for use inthe refining step. The mixture was agitated and 20.5 parts by weight of12% sodium hydroxide solution were added. The mixture was agitated 15minutes, the temperature being maintained at 130 F. The mixture was thenallowed to settle, the refined miscella being decanted from theprecipitated foots and subsequently filtered. The Lovibond color of a 5%inch column of this refinedmiscella was 35 yellow, 3.5 red. The samemiscella refined under comparable conditions without the addition of thepolypropylene rlycol was too dark to read on the Lovibond scale.

In the further testing of the invention substantially in accordance withExample 1, refinings of cottonseed oil miscella at F. with 15 minutesagitation, of the maximum percentage of 12% sodium hydroxide being used,gave the following specific color results when the indicated amounts ofnon-ionic ethers were used. It should be noted here that in all casescomparable refinings without the use of the non-ionic ether resulted inrefined miseellas which were Per Cent Color-of Refined bigger Miscellaon Non Ionic Ether caustic Soda Yellow Red Soln Monothioether of dodecylmerca tan and polyethylene glycol contai lng about 10 ethylene grou s0.6 30 2. 2 Monoether of tall oil an polyethylene 1 glycol containingabout 10 ethylene groups 0. 6 30 2. 3 Monoether of polyethylene glycoland sorbitan monooleate (a commercial product sometimes referred to asTween 81) 0. 6 25 0. 9 Monoether of polyethylene glycol and sorbitanmonooleate (a commercial product sometimes referred -to as Tween 81) 0.22 20 1.8 Monoether of polyethylene glycol and sorbitan monooleate (acommercial product sometimes referred to as Tween 81) 0. 11 30 4. 9Monoether of polyethylene glycol and sorbitan monooleete (a commercialproduct sometimes referred to as Tween 81) 0.05 30 8.8 Monoether ofoctylphenol and polyethylene glycol containing about 10 ethylene groupsl. 2 60 M Monoester of octaethylene glycol and the fatty acids ofcottonseed oil hydro genated to about 70 I. V 0. 6 20 1.3 Monoether ofdodecyl phenol and hexadecaethylene glycol 0. 6 30 2.8 Dipropylcneglycol 0.625 35 3. 2 Reaction product of one mol monoethanolamine andsix mols of ethylene oxide 0. 625 35 3. Reaction product of one mol of amixture of amines derived from coconut oil and six mols of ethyleneoxide 0. 5 20 2. 1

Example 2.-To 250 cc. of soybean oil miscella (at about 80 F.)containing about 40% oil were added .11 gram of polypropylene glycolhaving a molecular weight of about 400. To th stirred mixture were thenadded 18 grams of 12% aqueous sodium hydroxide solution. The mixture wasagitated for 15 minutes, the temperature being maintained at about 80 F.

In this example the amount of sodium hydroxide used was 150% of the N.C. P. A. maximum and the amount of polypropylene glycol was 0.625% ofthe weight of the lye. Y

The refined miscella had a color of 30 yellow, 5.0 red, whereas the samemiscella refined in a comparable way without the use of thepolypropylene glycol had a color of 70 yellow, 11.5 red.

Example 3.-The ether formed by the condensation of octylene glycol withabout 7 mols of ethylene oxide was used in this example.

To 250 cc. of cottonseed oil miscella (at about 80 F.) containing about40% oil were added .23 gram of the ether. To the stirred mixture werethen added 11.3 grams of 12% aqueous sodium hydroxide solution. Thmixture was agitated at about 80 F. for 5 minutes.

In this example the amount of sodium hydroxide used was 125% of the N.C. P. A. maximum and the amount of non-ionic ether was 2.0% of theweight of the lye.

The refined miscella had a color of 35 yellow, 4.9 red, whereas the samemiscella refined in a comparable way without the use of the ether had acolor of '70 yellow, 30 red.

Example 4.The conditions of refining the miscella of Example 3 wererepeated employing the ether resulting from the condensation of 2-methylpentanediol-2,4 with about '7 mols of ethylene oxide. The refinedmiscella had a color of 35 yellow, 4.8 red.

As an auxiliary example, one can obtain the benefits of the presentinvention by use of a mixture of the ether used in Example 4 withpolypropylene glycol having a molecular weight of about 400. a

As will be noted from the above examples, marked improvement in color isobtained when the amount of non-ionic ether employed is as low as 0.05per cent based on the weight of the ,lye. However. even smaller amountssuch as 0.02 per cent (based on the lye) or some oi. the more activeethers efiect noticeable improvement in color. Obviously all etherscovered in the present application are not equally effective in theirefilciency to promote removal of color and mixtures may be employed ifdesired. Amounts of some compounds such as the monobutyl ether ofethylene glycol and the diethyl ether of diethylene glycol, which arenecessary to achieve desired color in the refined miscella, may exceed 6percent of the weight of the lye and even greater proportions, such as10 per cent, may be necessary in some instances.

Instead of adding the non-ionic ether to the mlscella prior to additionof the lye as shown in the above examples, the addition may be madeseparately but simultaneously with the lye, or shortly after the lye hasbeen added, or in admixture with the lye, the essential requirementbeing that the non-ionic ether be present substantially throughout theperiod in which the lye and miscella are mixed.

Refined miscellas with markedly improved color were also obtained byagitating miscella with caustic soda solution in the presence of thefollowing non-ionic ethers not heretofore specifically mentioned.

Hexaethylene glycol Nonaethylene glycol Dodecethylene glycol Lauric acidmonoester of diethylene glycol Acetic acid diester of diethylene glycolLaurie acid diester of tetraethylene glycol Laurie acid diester ofnonaethylene glycol.

Stearic acid monoester of octaethylene glycol Monoester of octaethyleneglycol and coconut oil fatty acids Diethyl ether of ethylene glycolMonobutyl ether of ethylene glycol Dibutyl ether of ethylene glycolMonobenzyl ether of ethylene glycol Monoethyl ether of diethylene glycolDiethyl ether of diethylene glycol Monobutyl ether of diethylene glycolDimethyl ether of diethylene glycol Dimethyl ether of tetraethyleneglycol Dibutyl ether of tetraethylene glycol Dilauryl ether oftetraethylene glycol Monoether of dodecyl phenol and heptaethyleneglycol Monomethyl ether of octaethylene glycol Monoethyl ether ofoctaethylene glycol Monoether of octaethylene glycol and cholesterolMonoether of dodecyl phenol and decaethylene glycol Monomethyl ether ofdodecaethylene glycol Monoether of dodecaethylene glycol and cholesterolMonomethyl ether of hexadecaethylene glycol Reaction product of one molethylene dlamine and six mols of ethylene oxide Monoester of the fattyacids of cottonseed oil hydrogenated to about 70 I. V.-and thepolyglycol obtained by the condensation of one mol of monoethyl ether ofdiethylene glycol with two mols of ethylene oxide 7 Monoester of thefatty acids of cottonseed oil hydrogenated to about 70 I. V. and thepolyglycol obtained by the condensation of one mol of monoethyl ether ofdiethylene glycol with six mols of ethylene oxide Monoester of the fattyacids of cottonseed oil hydrogenated to about 70 I. V. and thepolyglycol obtained by the condensation of one mol of monoethyl ether ofdiethylene glycol with eight mols of ethylene oxide Monoester of thefatty acids of cottonseed oil hydrogenated to about 70 I. V. and themonoethyl ether of tetraethylene glycol Monoester of the fatty acids ofcottonseed oil hydrogenated to about 70 I. V. and the monoethyl ether ofoctaethylene glycol Monoester of the fatty acids of cottonseed oilhydrogenated to about 70 I. V. and the monoethyl ether of decaethyleneglycol Polypropylene glycol of about 300 mol. wt. (Wyandotte Chem. Corp.Sample -2990, Pluracol P-284) about pentapropylene glycol Ether-glycolderived by the reaction of one mol coconut oil fatty alcohols with 1.8mols isobutylene oxide Ether-glycol derived by the reaction of one molcoconut oil fatty alcohols with 2.4 mols isobutylene oxide Alphamonobutyl ether of glycerol Monoester of the fatty acids of cottonseedoil hydrogenated to about 70 I. V. and diglycerol Polyglycoi of about300 mol. wt. prepared from a mixture of 2.6 mols ethylene oxide and 1mol propylene oxide prepared byWyandotte Chem. Corp. and sometimesreferred to as Puracol 2.6-M-298 Polyglycol obtained by reacting 1 molethylene glycol with 3 mols isobutylene oxide Monomethyl ether of apolyglycol prepared by the reaction of two mols ethylene oxide with onemol propylene oxide (Wyandotte Chem. Corp. Sample 0-2897, AlkylPluracol) Monopropyl ether of a polyglycol prepared by the reaction oftwo mols ethylene oxide with. one mol propylene oxide (Wyandotte Chem.

Corp. Sample 0-2894, Alkyl Pluracol) From the above it is clear that thenumber of compounds which may be successfully used in the practice of myinvention is very great. Of outstanding preference, however, are thosepolyglycols containing at least two glycol units, each unit containingfrom two to four carbon atoms, and derivatives of such polyglycols inwhich the hydrogen atoms of one or both hydroxyl groups are substitutedby etheriflcation with alkyl groups containing from one to eighteencarbon atoms.

The above description of the invention has been confined specifically tomiscellas obtained in the extraction of cottonseed oil and soybean oil,and the invention is of particular importance in the case of cottonseedoil miscellas. However, the advantage of improved color obtainable withreduction in lye usage and with reduction in agitation time in thepractice of the invention is realizedin the refining of miscellasobtained in the solvent extraction of other oleaginous materials.

Moreover, although the specific description of the invention hasbeen-related to batch refining. it is to be understood that theadvantages of my contribution may also be realized in continuousrefining procedures employing continuous mixing of miscella and lyefollowed by continuous centrifugal separation of the refined miscellaand precipitated foots.

Having thus described my invention, what I claim and desire to secure byLetters Patent is:

1. In the process of refining vegetable oils in solution in volatilesolvents, the step of agitating said solution with an aqueous solutionof sodium hydroxide in the presence of at least one nonionic compound,liquid at about F.. and of the group consisting of (l) ethers ofpolyhydric alcohols, said alcohols containing from two to three hydroxygroups and having from two to eight carbon atoms in the carbon skeletonthereof, and (2) non-ionic organic derivatives of such of said ethers ascontain unreacted hydroxyl groups.

2. The process of claim 1, in which the designated compound is apolyglycol containing at least two glycol units, each unit containingfrom two to four carbon atoms.

3. The process of claim 2, in which the designated compound ispolypropylene glycol having a molecular weight of about 400.

4. The process of claim 2, in which the hydrogen atom of one hydroxylgroup of the polygiycol is substituted.

5. The process of claim 2, in which the hydrogen atom of one hydroxylgroup of the polyglycol is etherifled.

6. The process of claim 2, in which the hydrogen atom of one hydroxylgroup of the polygiycol is substituted with an alkyl group having from51 to 1-8 carbon atoms.

7. The process of claim 2, in which the hydrogen atoms of both hydroxylgroups of the polyglycol are substituted.

8. The process of claim 2, in which the hydrogen atoms of both hydroxylgroups of the polyg lycol are etherified.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,190,589 Clayton Feb. 13, 19402,278,838 De Groote Apr. 7, 1942 2,307,058 Moeller Jan. 5, 1943

1. IN THE PROCESS OF REFINING VEGETABLE OILS IN SOLUTION IN VOLATILESOLVENTS, THE STEP OF AGITATING SAID SOLUTION WITH AN AQUEOUS SOLUTIONOF SODIUM HYDROXIDE IN THE PRESENCE OF AT LEAST ONE NONIONIC COMPOUND,LIQUID AT ABOUT 80* F., AND OF THE GROUP CONSISTING OF (1) ETHERS OFPOLYHYDRIC ALCOHOLS, SAID ALCOHOLS CONTAINING FROM TWO TO THREE HYDROXYGROUPS AND HAVING FROM TWO TO EIGHT CARBON ATOMS IN THE CARBON SKELETONTHEREOF, AND (2) NON-IONIC ORGANIC DERIVATIVES OF SUCH OF SAID ETHERS ASCONTAIN UNREACTED HYDROXYL GROUPS.